Improved Postharvest Quality of Cold Stored Blueberry by Edible Coating Based on Composite Gum Arabic/Roselle Extract

The present work aimed at evaluating the efficacy of gum Arabic-based edible coating enriched with red and white roselle extracts, on the postharvest quality of blueberry fruits during storage at 4 +/- 0.5 degrees C. Physicochemical, phytochemicals, antioxidant capability, decay percent, and microbiological analyses of coated and uncoated blueberries were performed. The change rates of polyphenol oxidase (PPO) and guaiacol peroxidase (POD) activity were also measured. The coatings (gum Arabic with or without roselle extract) inhibited the growth of microbes (yeast and mesophilic aerobic bacteria) and enzyme activities (POD and PPO) of blueberries, reduced the degradation of anthocyanins and total phenolic as well as the weight loss and decay, and improved the firmness of blueberries. In comparison with gum Arabic coating, the gum Arabic enriched with roselle extract coating showed better performance on reducing microbes, enzyme activities, and anthocyanins degradation while enhancing the total phenolic content and decreasing the decay percentage. No significant differences were observed between the coated and uncoated blueberries in terms of their antioxidant capacities and pH values (p > 0.05). In conclusion, the combination of gum Arabic and roselle extract as edible coating materials can be used to conserve the quality of blueberry.